What is the third heaven?

I know a man in Christ who fourteen years ago was caught up to the third heaven–whether in the body or out of the body I do not know, God knows.

To understand what he meant, we need to know that “heaven” is used in three ways in Jewish cosmology.

Heaven=atmosphere (“where the birds fly”).

Heaven=outer space (“where the stars are”).

Heaven=spiritual realm (“where God lives”)

Many commentators believe that Paul is referring to the “third heaven” in Jewish cosmology. i.e., where God lives. In any case it is only a vision as he makes clear in v 1 and v 7. So it may not have been a physical thing at all. If so then it is similar to the visions of Ezekiel (ch1 and 10) and Isaiah (ch6) where they had a vision of God’s dwelling place in heaven.

Another complication with this reference is that Paul may be giving not his own teaching but reply to the claims to the Judaist so-called “Super-Apostles” of 2 Corinthians 11:5. This section of Paul’s rebuttal 2 Corinthians 11:14 includes references to Second Temple period early rabbinical traditions known today as the “Life of Adam literature”. See the answer to How does Satan disguise himself as an angel of light? for more information on that. A trip to the “third heaven” and “paradise” occurs in that material to in the legendary context of the burial of Adam. So it is possible that 12:2 is partly Paul throwing back the Superapostles’ own teaching at them, rather than it being Paul’s own teaching. It is notable Paul never returns to the subject of “Third Heaven” or any of the other fanciful Life of Adam rabbinical traditions except here in 2 Corinthians ch.11-12 where his is rebutting the Superapostles’ claims.